If it won't move with the cable detached and the limits screws backed off, there has to be something jammed into the der or something bent somewhere. But I can't see anything from the photos. I would just note that it takes a surprising amount of force to move a front der by hand. A lot more than a rear der. Are you sure it's really stuck?

(09-10-2010, 06:04 PM)rockyraccoon Wrote: wouldn't the "resting position" of the front derailleur be on the small chainring?

95% of the time, yes. (Except for oddball derailleurs that have the outer as their resting position.) This brings up a good point though. Unless you really back the limits screws all the way out, the derailleur should be resting on one of them if the cable is detached. Sounds like either something got jammed in there or you bumped the der and it is hitting against something. Time to "poke around".

looks to me like the rust bug has bitten, you can see in the 2nd pic that the limit screws are rusty and not in contact with the stop, if it wont move at all, you can try removing it from the bike and freeing it up by hand, you may be lucky, but my experience is it wont last long before it sticks again, I would think about replacing it.

Hi there, thanks for the help. I am thinking about replacing it however I have no idea which one to choose and whether it will be compatible or not. The bike is a MTB GT (3 x 7 spd). The shifters and cables are shimano and the rd is also shimano XTR.

There is no real reason not to use the same make and model, is there?
Fronts are not as critical as rears, but you need to watch out for;
it matches the same no. of teeth on your top ring, the clamp dia. and whether it is top or bottom pull.

You can try taking it off, dismantling and cleaning but Acera is pretty much cheap as, entry level stuff it is pretty straight forward to replace so I would advise this like for like.

Are you sure that the rest is XTR? didn't think there was such a thing as 7 speed XTR and it would be very unusual for a bike to come assembled with a mixture of high end and entry level stuff.

As far as upgrading is concerned you have quite a bit to think about, it depends what you do with the bike. If you use the bike for downhill MTBing then go with XT or XTR but if you are just using on a casual basis or going to the shops go with any Acera , Deore or Deore LX 3 speed FD ( it will work - whatever is available locally. - the price difference is $10 for a new Acera FD and about $2000 for a complete XTR system

I recently upgraded my hybrids drivetrain as I have been doing 300Km + per week on my commute to work (I certainly don't want to use my expensive road bike for commuting!), the stock Acera drivetrain was rattling around and needed replacing every few months. I had a spare 105 triple crankset knocking about - so I upgraded to Shimano Deore XT front & rear derailleurs, 9 speed cassette 9 speed Shimano LX Shifters and Avid brakes replacing the integrated 8 speed brakes and shifters. Despite Shimano hype on Front derailleur travel distances the 10 speed road crank works absolutely fine with the 9/3 speed MTB LX shifters and 9 Speed Ultegra chain.
The cost was about $500 for all this without the cost of the crank and I did all the work myself. The bike frame is pretty good and I have panniers and the like for going out camping with the kids so in this case it made sense to upgrade; in my experience it is usually a better idea to change the bike rather than upgrade.

(09-11-2010, 04:38 PM)trevgbb Wrote: There is no real reason not to use the same make and model, is there?

Thank you for the tips when choosing a replacement. Unfortunately, I can't find the same one online or in my LBSs. I'm in England.

(09-12-2010, 06:42 AM)JonathanSG Wrote: Are you sure that the rest is XTR? didn't think there was such a thing as 7 speed XTR and it would be very unusual for a bike to come assembled with a mixture of high end and entry level stuff.

Sorry, my mistake! Just double checked The fd is XTR while the cassette is shimano sis. The bike is a second hand bought from a friend who assembled himself.

(09-12-2010, 06:42 AM)JonathanSG Wrote: As far as upgrading is concerned...

I'm going to remove the fd and do a deep clean. If the problem cannot be solved by cleaning it I will get a new one, probably Deore as you suggested. Thanks!

(09-12-2010, 06:42 AM)JonathanSG Wrote: ... in my experience it is usually a better idea to change the bike rather than upgrade.

As Trevgbb pointed out make sure that your crankset is standard sizes. These are normally 22 - 32 - 42/44 teeth - up to 28-38-48 teeth. I am pretty sure that all of the deore front derailleurs will work on these sizes. They also come with a insert so it should fit most standard seat posts.